Grupo de Investigación en Optometría, Departamento de Óptica, Facultad de Física, Universitat de València, C/Dr. Moliner 50. Burjassot, Valencia, 46100, Spain,
Graefes Arch Clin Exp Ophthalmol. 2014 May;252(5):801-9. doi: 10.1007/s00417-014-2602-x. Epub 2014 Mar 18.
More accurate estimation of the general height of the visual field may improve our ability to detect and monitor progression of diseases affecting visual function such as glaucoma. General height (GH) can be affected by factors such as cataracts, pupillary miosis, refractive error, and learning and fatigue effects. The conventional GH index, consisting of subtracting the 85th largest value from the total-deviation map, has been shown to overestimate the height in patients with moderate and advanced glaucoma. We aimed at developing an improved estimator for general height based on ranking of total-deviation values that are within normal limits (GHr).
Two datasets were used for the comparisons between GH and GHr estimates: one with 369 visual fields for 102 controls, and another with 500 visual fields for 124 patients. For controls, we compared the distributions of mean of total deviation (MD) and of mean of pattern deviation (MPD) derived from both the GH and the GHr estimates. For patients, we assessed agreement between both estimates and between pairs of consecutive visits. We also compared linear fits in progression analyses. All data were collected with 24-2 SITA Standard.
For control subjects and patients with MD above -5.5 dB, estimates with the GHr estimator were not significantly different than with the GH estimator. For patients with glaucoma with MD below -5.5 dB, as MD became more negative the GH estimates were increasingly greater than GHr estimates. For patients with glaucoma, test-retest variability was lower with the GHr estimator: between visits agreement was better for GHr estimates than for GH estimates (SD of 0.8 dB versus 1.5 dB; p < 0.0001). Linear-regression analysis fitted better estimates obtained with the GHr estimator. Root mean square error for GHr was 0.4 dB; lower than the 0.8 dB for GH (p < 0.0001).
The novel GHr estimator is very different from the conventional GH estimator, has more solid foundations, and better statistical properties. Nevertheless, it is not always better than the GH estimator, in particular if no focal loss is present. Pattern-deviation maps obtained with GHr reduce systematic underestimation of glaucomatous damage.
更准确地估计全视野高度可能会提高我们检测和监测影响视觉功能的疾病（如青光眼）进展的能力。全视野高度（GH）可能会受到白内障、瞳孔缩小、屈光不正以及学习和疲劳等因素的影响。传统的 GH 指数由从总偏差图中减去第 85 大值组成，已被证明在中度和晚期青光眼患者中高估了高度。我们旨在开发一种基于总偏差值排序的改进全视野高度估计器（GHr）。
我们使用两个数据集来比较 GH 和 GHr 估计值：一个包含 102 名对照者的 369 个视野，另一个包含 124 名患者的 500 个视野。对于对照者，我们比较了来自 GH 和 GHr 估计值的平均总偏差（MD）和平均模式偏差（MPD）的分布。对于患者，我们评估了两种估计值之间以及连续两次就诊之间的一致性。我们还比较了进展分析中的线性拟合。所有数据均使用 24-2 SITA Standard 收集。
对于 MD 高于-5.5dB 的对照者和患者，使用 GHr 估计器的估计值与使用 GH 估计器的估计值没有显著差异。对于 MD 低于-5.5dB 的青光眼患者，随着 MD 变得更负，GH 估计值越来越大于 GHr 估计值。对于青光眼患者，使用 GHr 估计器的测试-重测变异性较低：GHr 估计值的两次就诊之间的一致性优于 GH 估计值（SD 分别为 0.8dB 和 1.5dB；p<0.0001）。线性回归分析拟合 GHr 估计器获得的估计值更好。GHr 的均方根误差为 0.4dB；低于 GH 的 0.8dB（p<0.0001）。
新型 GHr 估计器与传统的 GH 估计器非常不同，具有更坚实的基础和更好的统计特性。然而，它并不总是优于 GH 估计器，特别是如果没有局灶性损失的情况下。使用 GHr 获得的模式偏差图减少了对青光眼损害的系统低估。
